Convert ListImages to use reauth.

This commit does not work -- acceptance test 08-... is broken.
diff --git a/servers_test.go b/servers_test.go
index d95fa40..60c71c8 100644
--- a/servers_test.go
+++ b/servers_test.go
@@ -24,6 +24,10 @@
 	return nil
 }
 
+func (ta *testAccess) Reauthenticate() error {
+	return nil
+}
+
 func TestGetServersApi(t *testing.T) {
 	c := TestContext().UseCustomClient(&http.Client{Transport: newTransport().WithResponse("Hello")})